Updated 3:47 pm, Monday, December 10, 2012

The City Council, acting as the Stadium Authority, voted 5-1 to support an $878.6 million contract that calls for kicking off construction on the 68,500-seat stadium in July, about six months earlier than anticipated, and finishing by August 2014, in time for the exhibition season.

The 49ers, who have called San Francisco their home since their founding in 1946, could play just two more seasons in Candlestick Park before moving.

The authority members approved three resolutions - the other two involved insurance and construction oversight - with no discussion or public comment. Will Kennedy was the lone vote against the measures, saying he wanted to wait on a court decision on a challenge to the voter referendum approving the stadium project.

The state-of-the-art stadium, located next to the Great America theme park, will cost slightly more than $1 billion to build. An $850 million loan approved by the city in December will pay for most of it. Earlier this month, the National Football League agreed to give the team $200 million in loans and payments.

A joint venture of Turner Construction and Devcon Construction will design and build the 15-acre facility on what is currently a parking lot. If it doesn't wrap up by the 2014 season, it could pay penalties of as much as $20 million.

Rendering of proposed San Francisco 49ers stadium in Santa Clara as would be viewed from Tasman Drive.

Rendering of proposed San Francisco 49ers stadium in Santa Clara as would be viewed from Tasman Drive.

Photo: San Francisco 49ers

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Renderings of the 49ers stadium design are displayed at the team's New Stadium Preview Center in Santa Clara, Calif., on Tuesday, Sept. 27, 2011.

Renderings of the 49ers stadium design are displayed at the team's New Stadium Preview Center in Santa Clara, Calif., on Tuesday, Sept. 27, 2011.

Photo: Noah Berger, Special To The Chronicle

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A graphic displays the 49ers' stadium location at the team's New Stadium Preview Center in Santa Clara, Calif., on Tuesday, Sept. 27, 2011.

A graphic displays the 49ers' stadium location at the team's New Stadium Preview Center in Santa Clara, Calif., on Tuesday, Sept. 27, 2011.

Photo: Noah Berger, Special To The Chronicle

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This is an illustration depicting the proposed new San Francisco 49ers stadium in Santa Clara.

This is an illustration depicting the proposed new San Francisco 49ers stadium in Santa Clara.

Photo: San Francisco 49ers

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This is an illustration depicting the proposed new San Francisco 49ers stadium in Santa Clara.

This is an illustration depicting the proposed new San Francisco 49ers stadium in Santa Clara.

Photo: San Francisco 49ers

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Santa Clara approves plans for 49ers stadium

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But if the contractor finishes at least a week before the first exhibition game of that season, it will get a $5 million bonus, paid for in extra rent from the 49ers.

A group against the stadium, Santa Clara Plays Fair, has collected signatures to call for a referendum on the $850 million loan, saying voters were not fully informed of the financial risks when they approved the project by nearly 60 percent in June 2010.

The city has rejected the group's petitions, and the battle is expected to be settled in court.